Sack the pollsters! How did the experts get it so wrong in Britain and Israel?

Israeli Prime Minister Benjamin Netanyahu and his wife, Sarah, after pulling off a shock victory(Nir Elias/Reuters)

Pollsters in two general elections in two countries in the past two months have been so wide of the mark on the eve of the vote that it has been embarrassing.

In both Israel, on 17 March, and Britain, on 7 May, respected polling organisations were forecasting a neck-and-neck race between the ruling parties and the main opposition.

In Israel, exit polls on the main TV stations forecast that Benjamin Netanyahu's Likud Party and Isaac Herzog's Zionist Union were on track to receive 25 seats each in the 120-member Knesset (Parliament). In reality, Likud won 31 while ZU managed 25.

In Britain, polls were consistently showing that it was too close to call between the Conservatives and Labour. Even on 6 May, the last polls had barely a cigarette paper between them when it came to polling figures.

So what went wrong?

In the UK, Professor Tim Bale, the chair of politics at Queen Mary, University of London, told Australia's ABC: "It's really hard to believe that so many of them have been so wrong for so long. We had 11 polls come out over the last couple of days, all of which show the parties, Labour and Conservative pretty much neck and neck.

"The pollsters are really going to have to go back to the drawing board and think about what went wrong unless there was some kind of massive late swing towards the Conservatives and I guess, you know, research might show whether that was the case or not."

In Israel, embarrassed pollsters said they were blindsided by reticent rightist voters and may have unwittingly prodded waverers to back the incumbent.

Channel 2 TV's veteran pollster Mina Tzemach said many Likud voters declined to take part in replicating their vote in the dummy ballot boxes set up by survey-taking companies outside voting stations.

Even though exit polls are anonymous, she suggested such reticence might have cultural roots for Israelis originally from countries with different political regimes in which they worry about sharing their private voting choices.

"In certain voting stations, voting stations in places where there are a lot of new immigrants, pro-Likud ballot boxes, the per cent of those who voted [in the exit polls] was especially low," Tzemach told Israel's Army Radio.

Fellow pollster Camil Fuchs agreed, saying final counts from voting stations he had monitored showed that a significant number of Likud supporters had not participated in exit polls.

"Some people don't say [in exit polls] what they really voted, and the exit polls close about two hours before the voting booths," Fuchs told Israel Radio.